【作者】 吴兰；

【导师】 余宁梅；

【作者基本信息】 西安理工大学 ， 微电子学与固体电子学， 2009， 博士

【摘要】 自从上世纪八十年代以来,空间光调制器作为实时光学信息处理、光计算和光学神经网络等系统的关键器件,得到了迅速发展。特别是由于半导体加工工艺的提高,GaAs多量子阱空间光调制器凭借其响应快、调制比大、调制灰度高、功耗低等突出优点已成为光通信领域内的研究热点。驱动电路是保证多量子阱空间光调制器正确工作及良好工作性能的关键模块,因此设计制作与之匹配的低功耗、高性能的驱动电路对多量子阱空间光调制器的发展具有重要意义。针对多量子阱空间光调制器的应用需求,本文研制了一款64×64阵列256级调制灰度的多量子阱空间光调制器驱动芯片。主要研究内容如下：1、针对空间光调制器非线性反射谱线难以直接转换为对应的线性电信号的问题,提出了“软件预处理”的概念。采用软件拟合的方法将非线性光信号转换为线性电信号,在不占用硬件资源的情况下,较好的完成了光电信号的关系转换。并且具有易于更改,灵活性强的特点；可处理各种不同的反射谱线,增强了驱动电路的通用性。2、为了解决高分辨率驱动电压带来的像素面积过大的问题,提出了二次扫描积分的方法。该方法根据目标电压值将积分升压过程分解为二个不同时钟频率的处理过程,先大幅升压,再调节精度。在保持驱动电压分辨率不变的基础上,将一次扫描积分中像素单元面积减小了一半,同时还大大降低了时钟频率,减小了时钟频率过快带来的各种不良影响。3、通过对电流源开关网络开关噪声产生机理的深入分析,设计了一款新型的开关网络结构。该结构将开关对电容的噪声影响转移为对电流源MOS管控制栅的噪声影响,并将开关噪声的幅度有效的控制在电流源的误差允许范围内,从而成功的对积分电容进行噪声隔离,消除了MOS管开关的非理想特性对积分电压精度的影响。该结构在保持电路结构简单、功耗低的同时,提高了输出精度。4、设计了一款与温度、电源无关的带隙基准电流源。该电流源利用三极管自身的正、负温度特性,产生一个与温度无关的参考电压；并使用运算放大器构成负反馈环路提高电源抑制比,从而使输出电压与电源电压无关；通过外置电阻最大程度的减小基准电流受温度的影响。测试结果表明该电流源的温度系数为8.7×10-6/℃,在2.6V-4V的电源电压下均能正常工作,达到了系统要求。5、通过对4×4阵列电流放大法驱动电路、2×4阵列电阻放大法驱动电路的设计、仿真、投片及测试,对驱动电路像素单元的结构、性能及精度进行了深入分析。进一步改进电路结构,最终完成了64×64像素阵列驱动芯片的投片及测试。芯片测试结果表明,芯片具有较好的工作性能,其驱动电压摆幅接近于0-VDD,驱动电压分辨率可调,最高可达256级。在50MHz的时钟频率下,帧速可达到20K／s。像素单元的版图面积仅为65μm×65μm,能够与多量子阱空间光调制器倒装在一起,满足多量子阱空间光调制器对驱动电路的各种要求。更多还原

【Abstract】 As a key component of real-time optical information processing, optical computing and optical neural network system, spatial light modulator (SLM) has been developed rapidly since 1980s. In particular, the multiple-quantum-well (MQW) SLM has become to a hot area of optical communication research, with its advantages of fast response, large modulation ratio, high gray scale modulation, low power consumption and so on. Driving circuit is the key to ensure performance of MQW SLM, so that it is great significance to in-depth study. To meet application requirements of MQW SLM, a 64×64 pixel array driver chip of MQW SLM is developed in this paper. The main contents are listed as follows:1. To translate the nonlinear reflectance spectrum of MQW SLM into the corresponding linear electrical-signals directly, a "software preprocessing" concept is put forward. In order to don’t take up the hardware resources, the nonlinear optical-signal is converted into the linear electrical-signal using a software fitting method. This method has the advantage of high flexibility and commonality.2.In order to reduce the pixel size, a new method of two-step integral is applied. In this method, the integral-voltage raising process is split into two steps with different clock frequency. The first step is rough-scan, and the second one is final-adjustment. While keeping the resolution of driving voltage, the pixel area of driving circuit is reduced by half, and the clock frequency is reduced.3. By analyzing the generation mechanism of the switching noise, a new structure of switch-network is developed. In this switch-network, the effect caused by switching noise on the capacitor is shifted on the MOS transistor gate, and the switching noise is effectively limited within error tolerance of the current source. Thus the noise on capacitor is isolate, and the integral-voltage precision is improved. The new structure has the advantages of the simpler structure, the lower power dissipation and the higher output precision. 4. A band-gap current source which is independent to the temperature and the power voltage is developed. A reference voltage is generated by using the positive and negative characteristic of the crystal triode itself. The Power Supply Rejection Ratio is improved by using an operational amplifier which constitutes the degenerate loop. The temperature effect on the band-gap current is reduced by using an off chip resistor. The experiment results show that the temperature coefficient of the band-gap current source is 8.7×10-6/℃and it works well within 2.6V-4V power supply.5. The design, simulation, tape-out and the chip test of the driving circuits for the 4x2 pixels,4×4 pixels is completed. After the analyzing pixel structure, performance and precision, an improved circuit structure of 64×64 pixel array driver chip is designed and tested. The experiment results show that the chip can offer the swing of the driving voltage from 0 up to VDD and the resolution of the driving voltage from 0 to 256. Besides, the pixel of driving circuit is compressed into 65μm×65μm, which can be integrated with MQW SLM by flip-chip bonding. In a word, the driver chip could satisfy the design requirements of MQW SLM.更多还原